I. Field of the Invention
The field of the invention comprises methods for the manufacture of thin films for manufacture of semiconductor devices. More specifically, the invention comprises methods for the manufacture of multi-layered thin films comprising an oxide such as SiO2 and an organic polymer such as poly(chloro-p-xylylene).
II. Discussion of Related Art
Both the synthesis and understanding of multilayer polymer/ceramic structures are important for many applications (Sanchez, Physics of Polymer Surfaces and Interfaces, Butterworth-Heinemann, Boston, Mass. (1992)). Among these applications are the need for thin film polymers for electronic packaging, coatings, passivation layers, lubrication, biocompatible materials, and intermetallic dielectrics for ULSI devices. Currently, a major need exists to replace silicon dioxide (SiO2) with a low dielectric constant material such as a polymer to reduce RC-delay, power consumption and cross-talk in ultra large scale integration (USLI) devices (Moore et al., Microelectronics Technology ACS symposium series 614: 449-70 (1995); Zhang, Thin Solid Films 270:508-511 (1995); Majid, J. Electron. Mat. 18(2):301-311 (1989); Whittington et al., IEEE Trans. CHMT 1(4):416-222 (1978)).
However, before integrating a totally polymeric intermetallic dielectric, different hybrid integration schemes have been proposed (Zhao et al, T.E. Seidel Mat. Res. Soc. Symp. Proc. 427:415-426 (1996)). They use SiO2 and functionalized poly(p-xylylene) derivatives to take advantage of the good adhesion properties and thermal stability of SiO2 while also taking advantage of the polymer""s low dielectric constant which would ultimately reduce the RC-delay in ULSI devices. The ability to deposit SiO2 and a polymer by the methods of chemical vapor deposition at the same temperature and pressure would reduce the processing expense for these hybrid structures and other applications which rely on multilayer structures.
The previous methods for depositing SiO2 use high temperatures or plasma processes prohibitive for the CVD of polymers. High deposition temperatures for SiO2 deposition would necessitate separate deposition chambers, one at high temperature for SiO2 deposition, and another at low temperature for polymer deposition. Plasma processes add defects to the polymer structures, and thermal CVD method for SiO2 deposition is appropriate for polymer/SiO2 CVD of multilayer structures.
Polymers themselves have complex anisotropic morphological structures. However, with the presence of SiO2, specific interactions and physical confinement causes the thin film polymers to have an even more complex morphology (Bitsanis et al., J. Chem. Phys. 92(6):3827-3847 (1990); Prest et al., J. Appl. Phys. 50(10): 6067-6071 (1979); Prest et al., J. Appl. Phys. 51(10): 5170-5174 (1980)). One very noticeable effect the specific interactions and physical confinement have on the polymer is its crystallization behavior due to the cooperative motion of the polymer chains (Frank, Science 273:912-915 (1996); Despotopoulou et al., Macromolecules 29:5797-5804 (1996); Billon et al., Colloid Polym. Sci. 272:633-654 (1996); Billon et al., Colloid Polym. Sci. 267:668-680(1989); Escline et al., Colloid Polym. Sci. 262:366-373 (1984)). These studies looked at the polymer crystallization of spin-coated polymer ultra-thin films which are wet-chemical deposition techniques. However, independent of the deposition method, the effect of constrainment reduces the mobility of the ultra-thin polymeric films.
Further, spin-coated or dip-coated methods for depositing thin films are not advantageous in fabricating ULSI devices due to low processing throughput, inability to fill gaps, poor conformality of the film, incorporation of impurities into the film and the presence of solvent used to dissolve the film precursor, which is an environmental concern.
Other techniques exist for producing multilayer structures of alternating ceramic and polymer or alternating metal and polymer layers (Akelah et al., Letters 22:97-102 (1995); Vaia et al., Chem. Mater. 5:1694-1696 (1993); Fukushima et al., J. Chem. So., Chem. Commun. 241-242 (1995); Lvov et al., Lanamuir 12:3038-3044 (1996); Messersmith et al., Chem. Mater. 5:1064-1066 (1993)). However, these methods all require high temperature deposition of the ceramic layers, and therefore require changing deposition conditions for each layer. This decreases the efficiency of manufacturing by increasing the time needed to deposit the multilayered films.
Therefore, future methods for manufacturing integrated circuits must be developed to deposit multilayer structures at temperatures below the threshold temperature of the polymer, permitting the concurrent or sequential deposition of both the ceramic and organic polymer dielectric materials. The threshold temperature of the polymer is that temperature above which polymer deposition is not possible due to lack of physisorption of the reactive intermediates. The physisorption of a reactive intermediate is a function of the molecular weight, polarizability and structure of the intermediate. The reactive intermediates, in turn, are generated from the thermally dissociated precursor and are transported to a low temperature chamber where deposition and polymerization occur.
Therefore, one object of the invention is the development of methods for manufacturing thin films with low dielectric constant, high dielectric strength, high thermal stability, and high mechanical strength.
A further object of the invention is the manufacture of thin films at temperatures near or below room temperature.
A yet further object of the invention is the development of methods of manufacturing multilayered thin films at temperatures near or below room temperature.
An additional object of the invention is the manufacture of films with graded properties of dielectric constant, refractive index, and adhesion as a function of thickness.
This invention comprises methods for the deposition of oxide and polymer dielectric materials to form thin films for semiconductor manufacture.
Thus, one aspect of the invention comprises the development of methods for the deposition of alternating layers of oxide dielectric and organic polymer.
An additional aspect of the invention comprises the co-deposition of oxide and organic polymer dielectric layers at temperatures near or below room temperature.
A further aspect of the invention comprises a thin film made by deposition of alternating layers of oxide and organic polymer, each deposited at temperatures near room temperature.
Another aspect of the invention comprises a multilayered thin film with a dielectric constant lower than that of a pure oxide thin film.
Yet another aspect of the invention comprises a thin film with thermal stability and mechanical strength greater than that of a pure organic polymer thin film.
Another aspect of the invention comprises the manufacture of a semiconductor chip having a dielectric material with alternating layers of oxide and organic polymer.
A yet further aspect of the invention comprises the manufacture of a semiconductor device comprising a semiconductor chip with a dielectric material having alternating layers of oxide and organic polymer.